Measurement of dielectric constant and loss factor of the dielectric material at microwave frequencies

Progress In Electromagnetics Research (Impact Factor: 1.23). 01/2007; 69:47-54. DOI: 10.2528/PIER06111204


A new technique to evaluate the dielectric constant and loss factor of a homogeneous dielectric material using rectangular shaped perturb cavity has been developed. The values of S-parameters are measured experimentally by placing the sample in the center of the cavity resonator. Sample under test is fabricated in the form of a cylinder. The real and imaginary part of the permittivity can be then calculated from the shift in the resonance frequency and Q-factor. The results of a Teflon sample are also tabulated.

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    • "Over the years, numerous methods have been used to calculate the í µí±‡/í µí±… coefficient of samples at microwave frequency . In the recent, Dudek et al. (1992) and Kumar et al. (2007), the vector network analyzer (VNA) has been used successfully to obtain the í µí±† parameters of samples in the microwave wave range [1] [2]. A new approach is presented that relies upon 3D electromagnetic simulation results to characterize and calculate the í µí±‡/í µí±… coefficient using FEM. "
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    ABSTRACT: PTFE samples were prepared with different thicknesses. Their electric field intensity and distribution of the PTFE samples placed inside a rectangular waveguide were simulated using finite element method. The calculation of transmission/reflection coefficients for all samples thickness was achieved via FEM. Amongst other observable features, result from calculation using FEM showed that the attenuation for the 15 mm PTFE sample is −3.32 dB; the 30 mm thick PTFE sample has an attenuation of 0.64 dB, while the 50 mm thick PTFE sample has an attenuation of 1.97 dB. It then suffices to say that, as the thickness of the PTFE sample increases, the attenuation of the samples at the corresponding thicknesses increases.
    Full-text · Article · Apr 2014 · Advances in Materials Science and Engineering
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    • "So, in the case of a given set of various materials it is necessary to adapt the existing measurement methods to determining its dielectric properties in a way enabling complex evaluation of behaviour of multimaterial systems in electromagnetic field. From among many methods[3,4]described in literature, the most often suggested for measurements of these properties are: perturbation method[5,6]and measurement of standing wave ratio on a stand of microwave slot line[3]. "
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    ABSTRACT: In the paper presented are results of a research on influence of electrical and physico-chemical properties of materials being parts of multicomponent and multimaterial systems used in foundry practice on efficiency and effectiveness of microwave heating. Effectiveness of the process was evaluated on the grounds of analysis of interaction between selected parameters of permittivity and loss factor, as well as collective index of energy absorbed, reflected and transmitted by these materials. In the examinations used was a stand of waveguide resonance cavity for determining electrical properties and a stand of microwave slot line for determining balance of microwave power emitted into selected materials. The examinations have brought closer the possibility of forecasting the behaviour of multimaterial systems like e.g. model, moulding sand or moulding box in microwave field on the grounds of various electrical and physico-chemical properties. On the grounds of analysis of the results, possible was selecting a group of materials designed for building foundry instrumentation to be effectively used in electromagnetic field.
    Full-text · Article · Mar 2014
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    • "It must be stressed that the rectangular cavity has been effectively employed as a device for permittivity measurements [19], [20] since, despite its narrow band, it allows Fig. 1. Sketch of the rectangular waveguide cavity. "
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    ABSTRACT: This paper presents 1 the design, fabrication, and characterization of a microwave resonator as a tool for concentration measurements of liquid compounds. The sensing device is a rectangular waveguide cavity tuned at 1.91 GHz, which exploits the fundamental TE101 mode in a transmission-type configuration. The coupling structure is optimized by means of a finite element code so as to achieve a high Q-factor. According to the type of substance inside the mixture, its concentration is conveniently related to changes of the S21 scattering parameter (transmission coefficient) in terms of: 1) resonance frequency; 2) 3-dB bandwidth; and 3) amplitude at the resonance frequency. Experimental tests on liquid solutions in controlled conditions are presented to evaluate the performance of the device.
    Full-text · Article · May 2013 · IEEE Sensors Journal
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